gmem: Add g_free_sized() and g_aligned_free_sized()

These wrap `free_sized()` and `free_aligned_sized()`, which are present
in C23[1]. This means that user code can start to use them without checking
for C23 support everywhere first.

It also means we can use them internally in GSlice to get a bit of
performance for the code which still uses it.

See https://en.cppreference.com/w/c/memory/free_aligned_sized and
https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2699.htm.

[1]: Specifically, section 7.24.3.4 of the latest C23 draft at
https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3088.pdf.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>

docs/reference/glib/glib-sections.txt.in

@@ -1082,6 +1082,7 @@ g_try_realloc_n
 
 <SUBSECTION>
 g_free
+g_free_sized
 g_clear_pointer
 g_steal_pointer
 g_mem_gc_friendly
@@ -1096,6 +1097,7 @@ g_newa0
 g_aligned_alloc
 g_aligned_alloc0
 g_aligned_free
+g_aligned_free_sized
 
 <SUBSECTION>
 g_memmove

glib/gmem.c

@@ -220,6 +220,9 @@ g_realloc (gpointer mem,
  * 
  * Frees the memory pointed to by @mem.
  *
+ * If you know the allocated size of @mem, calling g_free_sized() may be faster,
+ * depending on the libc implementation in use.
+ *
  * If @mem is %NULL it simply returns, so there is no need to check @mem
  * against %NULL before calling this function.
  */
@@ -230,6 +233,33 @@ g_free (gpointer mem)
   TRACE(GLIB_MEM_FREE((void*) mem));
 }
 
+/**
+ * g_free_sized:
+ * @mem: (nullable): the memory to free
+ * @size: size of @mem, in bytes
+ *
+ * Frees the memory pointed to by @mem, assuming it is has the given @size.
+ *
+ * If @mem is %NULL this is a no-op (and @size is ignored).
+ *
+ * It is an error if @size doesn’t match the size passed when @mem was
+ * allocated. @size is passed to this function to allow optimizations in the
+ * allocator. If you don’t know the allocation size, use g_free() instead.
+ *
+ * Since: 2.76
+ */
+void
+g_free_sized (void   *mem,
+              size_t  size)
+{
+#ifdef HAVE_FREE_SIZED
+  free_sized (mem, size);
+#else
+  free (mem);
+#endif
+  TRACE (GLIB_MEM_FREE ((void*) mem));
+}
+
 /**
  * g_clear_pointer: (skip)
  * @pp: (nullable) (not optional) (inout) (transfer full): a pointer to a
@@ -578,7 +608,7 @@ g_mem_profile (void)
  * the program is terminated.
  *
  * Aligned memory allocations returned by this function can only be
- * freed using g_aligned_free().
+ * freed using g_aligned_free_sized() or g_aligned_free().
  *
  * Returns: (transfer full): the allocated memory
  *
@@ -702,3 +732,33 @@ g_aligned_free (gpointer mem)
 {
   aligned_free (mem);
 }
+
+/**
+ * g_aligned_free_sized:
+ * @mem: (nullable): the memory to free
+ * @alignment: alignment of @mem
+ * @size: size of @mem, in bytes
+ *
+ * Frees the memory pointed to by @mem, assuming it is has the given @size and
+ * @alignment.
+ *
+ * If @mem is %NULL this is a no-op (and @size is ignored).
+ *
+ * It is an error if @size doesn’t match the size, or @alignment doesn’t match
+ * the alignment, passed when @mem was allocated. @size and @alignment are
+ * passed to this function to allow optimizations in the allocator. If you
+ * don’t know either of them, use g_aligned_free() instead.
+ *
+ * Since: 2.76
+ */
+void
+g_aligned_free_sized (void   *mem,
+                      size_t  alignment,
+                      size_t  size)
+{
+#ifdef HAVE_FREE_ALIGNED_SIZED
+  free_aligned_sized (mem, alignment, size);
+#else
+  aligned_free (mem);
+#endif
+}

glib/gmem.h

@@ -72,6 +72,9 @@ typedef struct _GMemVTable GMemVTable;
 
 GLIB_AVAILABLE_IN_ALL
 void	 g_free	          (gpointer	 mem);
+GLIB_AVAILABLE_IN_2_76
+void     g_free_sized     (gpointer      mem,
+                           size_t        size);
 
 GLIB_AVAILABLE_IN_2_34
 void     g_clear_pointer  (gpointer      *pp,
@@ -123,6 +126,10 @@ gpointer g_aligned_alloc0 (gsize         n_blocks,
                            gsize         alignment) G_GNUC_WARN_UNUSED_RESULT G_GNUC_ALLOC_SIZE2(1,2);
 GLIB_AVAILABLE_IN_2_72
 void     g_aligned_free   (gpointer      mem);
+GLIB_AVAILABLE_IN_2_76
+void     g_aligned_free_sized (gpointer  mem,
+                               size_t    alignment,
+                               size_t    size);
 
 #if defined(glib_typeof) && GLIB_VERSION_MAX_ALLOWED >= GLIB_VERSION_2_58
 #define g_clear_pointer(pp, destroy)                     \

glib/tests/utils.c

@@ -1142,6 +1142,39 @@ test_aligned_mem_zeroed (void)
   g_aligned_free (p);
 }
 
+static void
+test_aligned_mem_free_sized (void)
+{
+  gsize n_blocks = 10;
+  guint *p;
+
+  g_test_summary ("Check that g_aligned_free_sized() works");
+
+  p = g_aligned_alloc (n_blocks, sizeof (*p), 16);
+  g_assert_nonnull (p);
+
+  g_aligned_free_sized (p, sizeof (*p), n_blocks * 16);
+
+  /* NULL should be ignored */
+  g_aligned_free_sized (NULL, sizeof (*p), n_blocks * 16);
+}
+
+static void
+test_free_sized (void)
+{
+  gpointer p;
+
+  g_test_summary ("Check that g_free_sized() works");
+
+  p = g_malloc (123);
+  g_assert_nonnull (p);
+
+  g_free_sized (p, 123);
+
+  /* NULL should be ignored */
+  g_free_sized (NULL, 123);
+}
+
 static void
 test_nullify (void)
 {
@@ -1317,6 +1350,8 @@ main (int   argc,
   g_test_add_func ("/utils/aligned-mem/subprocess/aligned_alloc_nmov", aligned_alloc_nmov);
   g_test_add_func ("/utils/aligned-mem/alignment", test_aligned_mem_alignment);
   g_test_add_func ("/utils/aligned-mem/zeroed", test_aligned_mem_zeroed);
+  g_test_add_func ("/utils/aligned-mem/free-sized", test_aligned_mem_free_sized);
+  g_test_add_func ("/utils/free-sized", test_free_sized);
   g_test_add_func ("/utils/nullify", test_nullify);
   g_test_add_func ("/utils/atexit", test_atexit);
   g_test_add_func ("/utils/check-setuid", test_check_setuid);

meson.build

@@ -614,6 +614,8 @@ functions = [
   'fchmod',
   'fchown',
   'fdwalk',
+  'free_aligned_sized',
+  'free_sized',
   'fsync',
   'getauxval',
   'getc_unlocked',